Repairing Painted Hair on a Doll

We just bought an American Girl Bitty Baby off of eBay. It is in excellent shape, however, there is a few spots on the head where the "hair" or paint has been rubbed off. Does anyone know how I can make it look new again? Thanks for your help.

Try a Sharpie Pen or any indelible ink pen. I use it for a lot of things that have a scratch or a bit of color missing. Like when I have gotten bleach on my jeans or black pants. Just find the color that best matches and even if it is not exact, no one ever sees the difference. It has saved me a lot of stress and money. Sharpie comes in so many colors and shades. I've even used it on wood furniture, it works great.